Within the framework of the Euler equations, a numerical study of the structure of a self-similar flow for various types of negative Mach reflection during diffraction of a shock wave by a wedge is performed. Along with the known modes of double and triple Mach reflection, a qualitatively new mode of negative Mach reflection with multiple three-shock configurations is observed. Peculiarities of the transition from multiple Mach reflection to regular reflection when changing the wedge angle are noted.